JP2008307583A - Die and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for manufacturing a screw part having improved loosening preventive effect, and a manufacturing method therefor. <P>SOLUTION: One pair of flat dies 30, 40 are the dies for applying form-rolling to thread ridges 20 of a step-lock-bolt 10 having both flanks 21 and 22 formed in such a manner that flat parts 21a and 22a and tilted parts 21b and 22b alternately continue. Then, in the fixing side flat die 30, flat projecting line parts 33a and tilted projecting line parts 33b in the form-rolling surface 31 are respectively formed by electrical discharge machining with the use of flat electrical discharge parts 52a and tilted electrical discharge parts 52b of respective projecting lines 51 for electrical discharge machining arranged in an electrode 50 for electrical discharge machining, and further, the form-rolling surface 41 of the moving side flat die 40 is formed similarly. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a die for rolling a thread portion having a locking function and a manufacturing method thereof.

  Conventionally, step lock bolts shown in Non-Patent Documents 1 to 3 below are known as bolts having a screw portion having a locking function. This step lock bolt is provided with fine step portions and inclined portions on the flank of the screw thread of the bolt, and attempts to achieve bolt loosening prevention by plastic deformation of the screw thread or the mating member when the bolt is screwed. Is.

FIG. 7 is an explanatory view for explaining the shape of a rolling processed surface 110 in a pair of conventional flat dies 100 for rolling a step lock bolt. In FIG. 7, for convenience, a part of the rolling processed surface 110 of the fixed-side flat die 100 is partially illustrated among the pair of flat dies.
Normally, the thread of the step lock bolt as described above is obtained by holding the rolled product before forming the threaded portion between a pair of flat dies 100, which are a fixed flat die 100 and a moving flat die, and a predetermined pressing force. It is formed by rolling while adding.

  As shown in FIG. 7, a plurality of protrusions 120 having a shape almost opposite to the shape when the thread of the step lock bolt is developed on a flat surface are formed on the rolling processed surface 110 of the fixed flat die 100. It is provided in a substantially straight line having a certain inclination with respect to the side (see the hatched portion in FIG. 7). Each protrusion 120 on the rolled surface 110 is provided with a flank 121 having a shape almost opposite to the pressure side flank for rolling the pressure side flank of the screw thread, and the idle side flank of the thread is rolled. A flank 122 having a shape substantially opposite to the play-side flank is provided for manufacturing. Here, the pressure side flank is a flank that slidably contacts the flank of the mating member when fastened to the mating member such as a nut, and the play flank is the mating side when fastened to the mating member. The flank is separated from the member.

  The flank 121 is provided with step-like protrusions 121a and inclined protrusions 121b having shapes substantially opposite to the step part and the inclined part of the pressure-side flank so as to alternately continue. Further, the flank 122 is provided with step-like protrusions and inclined protrusions having shapes substantially opposite to the step part and the inclined part of the play side flank so as to be alternately continued. A plurality of protrusions having similar step-like protrusions and inclined protrusions are also provided on the rolling processed surface of the moving side flat die.

Journal of Materials Processing Technology Vol, 56, p321-332, "Evaluation of Anti-loosening Nuts for Screw Fasteners" H, Fujii et al. 1996. Transactions of the Japan Society of Mechanical Engineers, volume C, volume 62 (597), p1963-1968, “Development of screw fasteners that are extremely resistant to loosening”, Hiroshi Fujii, et al., 1996. Transactions of the Japan Society of Mechanical Engineers, volume C, volume 62 (596), p1527-1532, “Analysis of loosening mechanism of screw fastening body and development of loosening test method”, Hiroshi Fujii, et al., 1996.

  By the way, for example, the plurality of protrusions 120 on the rolling processed surface 110 of the fixed flat die 100 are formed by performing cutting using a cutting blade 130 on a metal material such as die steel (see FIG. 7). ). However, since die steel is generally high in strength, cutting is difficult and processing costs are high. Furthermore, there is a problem that the cutting blade 130 for cutting the die steel is quickly worn, and the shape of each protrusion 120 is not uniform when the worn cutting blade 130 is continuously used. .

  Further, when the above-described step lock bolt is fastened to the counterpart member, the pressure lock flank, which is one flank of the thread, is slidably contacted with the flank of the counterpart member. The screw loosening prevention action is exhibited by the stepped portion of the pressure side flank that switches from the step portion to the inclined portion in a ridge shape that bites into the mating member and the step portion slides against the mating member. Is done.

  As can be seen from FIG. 7, each of the above-described thread-like thread portions is a portion of the plurality of protrusions 120 that is a portion that switches from the step-like protrusion 121 a to the inclined protrusion 121 b in a valley shape. Each is rolled by 121c. Since each valley-shaped protrusion 121c is formed in a valley shape, when the step-shaped protrusion 121a and the inclined protrusion 121b are cut with the cutting blade 130, the valley-shaped protrusion 121c is The cutting blade 130 is formed in an R shape corresponding to the radius.

  When the step portion and the inclined portion in the pressure side flank are rolled by the fixed flat die 100 in which each valley-shaped protrusion 121c is formed in an R shape in this way, the tip portion of each mountain screw portion is formed in an R shape. Each is formed. For this reason, there has been a problem that each thread-like screw portion is unlikely to bite into the mating member, and the effect of preventing the screw from loosening is reduced. Moreover, the same problem also occurred in each valley-shaped protrusion on the rolling side surface of the moving side flat die.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a die for manufacturing a threaded portion with an improved locking effect and a method for manufacturing the same.

  In order to achieve the above object, in the die of claim 1 according to the claims, the flank (21) is formed so that the sections (21a) having a gentle lead angle and the sections (21b) having a steep lead angle are alternately arranged. ) Having a plurality of protrusions (32, 42) for rolling the threaded part (20) having a plurality of protrusions (30, 40), the plurality of protrusions having a loose lead angle. Step-shaped protrusions (33a) for rolling the sections and inclined protrusions (33b) for rolling the sections with a steep lead angle are formed alternately and continuously, The step-like protrusions and the inclined protrusions are formed by electric discharge machining using the step-like electric discharge part (52a) and the inclined electric discharge part (52b) provided on the electric discharge machining electrode (50). Characteristic.

  In order to achieve the above object, in the method for manufacturing a die according to claim 4, the sections (21a) having a gentle lead angle and the sections (21b) having a steep lead angle are alternately formed. It is a manufacturing method of a pair of dies (30, 40) provided with a plurality of projections (32, 42) for rolling a thread part (20) having a flank (21), For rolling the section having a loose lead angle by means of electric discharge machining by the step-like electric discharge part (52a) and the inclined electric discharge part (52b) provided on the electric discharge machining electrode (50). Technical features include an electric discharge machining step in which the stepped protrusions (33a) and the inclined protrusions (33b) are formed alternately in order to roll the steep section of the lead angle. And

  In the invention of claim 1, the plurality of protrusions in the pair of dies for rolling the thread portion having the flank formed so that the sections having a gentle lead angle and the steep sections are alternately continued are Stepped protrusions and inclined protrusions for rolling a loose section and a steep section are formed by electric discharge machining using stepped discharge sections and inclined discharge sections provided on the electrode for electric discharge machining, respectively. The

  At this time, in each of the plurality of ridges of the die corresponding to the pressure side flank of the threaded portion, each valley-shaped ridge that is a portion that switches from the step-shaped ridge to the inclined ridge in a valley shape, The electric discharge machining electrode is formed by electric discharge machining with each mountain-shaped discharge portion that is a portion that switches from a step-shaped discharge portion to an inclined discharge portion in an electric discharge machining electrode for electric discharge machining.

  Since each said mountain-shaped discharge part is formed in a mountain shape, when each step-like discharge part and each inclined discharge part in the electrode for electric discharge machining are machined by cutting using a cutting blade, etc., each said mountain-like discharge part The tip of each part is formed so as to have a corner that protrudes outward without being formed into an R shape.

  With the electric discharge machining electrode machined in this way, when the rolling process surface is formed by electric discharge machining in order to form each step-shaped projection and each inclined projection on the rolling process surface of the die, the above-mentioned As described above, since the tip portion of each mountain-shaped discharge portion is formed to have a corner portion protruding outward, each valley-shaped protrusion on the rolled surface is not formed into an R shape. It is formed to be square.

With a pair of dies processed in this manner, when a threaded portion having a flank formed so that the above-mentioned sections having a loose lead angle and a steep section are alternately continued on the workpiece, The tip portion of each thread-like screw portion, which is a portion where the lead flank in the side flank is switched from a loose lead angle portion to a steep portion, has a corner portion that protrudes outward without being formed into an R shape. Since it is formed, the respective thread-like screw portions easily bite into the mating member.
Therefore, it is possible to manufacture a threaded portion with an improved locking effect.

  In the invention of claim 2, the electrode for electric discharge machining is constituted by an electrode material having a lower strength than that of die steel generally used as a material for a rolling die, for example, an electrode made of a copper alloy material. For this reason, the electrode for electric discharge machining can be easily processed by using an electrode material having a lower strength than the die steel as the electrode for electric discharge machining.

  As a result, steps such as cutting of the electrode for electric discharge machining and steps such as electric discharge machining of the rolling surface of the die are added, but steps such as cutting of the rolling surface of the die that are difficult to work are performed. Since it is abolished, the work itself for machining the rolling surface of the die becomes easy and the workability is improved.

Furthermore, since machining of the electrode material with low strength is performed in machining of the electrode for electric discharge machining, wear of the cutting blade and the like is suppressed, so variation in the shape of the electrode for electric discharge machining due to wear of the cutting blade and the like is suppressed. Is done. For this reason, the processing accuracy of the plurality of protrusions on the rolling processed surface of the die formed by electric discharge machining using the electric discharge machining electrode is improved, and the processing accuracy of the threaded portion rolled by the die is also improved. .
Therefore, it is possible to manufacture a threaded portion that improves the locking effect and improves the processing accuracy.

  In the invention of claim 3, the stepped protrusion is formed by electric discharge machining by the stepped discharge part so that the lead angle of the section having a loose lead angle is rolled (zero) by the stepped protrusion. It is formed.

  As a result, the lead angle in the section where the lead angle of the thread portion is loose becomes zero, and in the section where the lead angle is zero, the axial force is directly changed to the frictional force, and the component force to rotate the screw is Since it does not work at all, the frictional force in the section where the lead angle is zero becomes stronger, and a stronger locking action is achieved.

In the invention of claim 4, as a method of manufacturing a pair of dies for rolling a thread portion having a flank formed such that a section having a loose lead angle and a steep section are alternately continued, a plurality of methods in both dies are used. Stepped protrusions and a steep lead angle section for rolling a section with a loose lead angle by electrical discharge machining with stepped and inclined discharge sections provided on the electrode for electric discharge machining Are formed so that the inclined projections are alternately continued.
Even if it does in this way, the die | dye which has an effect equivalent to the die | dye of the said Claim 1 can be manufactured.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view showing a bolt according to the present embodiment (hereinafter also referred to as a step lock bolt 10), and FIG. 1B is an enlarged perspective view of the screw thread 20 of FIG. 1A. It is.
As shown in FIG. 1 (A), the step lock bolt 10 is provided with a screw portion 11 having a thread 20 formed along a helical line. The screw thread 20 includes a pressure-side flank 21 (upper side of the thread 20 in FIG. 1A) that slides on the flank of the mating member when fastened to the mating member such as a nut, and a mating member. A play-side flank 22 (below the thread 20 in FIG. 1A) is formed.

  The pressure-side flank 21 is formed such that a section where the lead angle is 0 (zero) (hereinafter, flat portion 21a) and a section where the lead angle is steep (inclined portion 21b) are alternately continued. Further, in the play-side flank 22, similarly to the pressure-side flank 21, a section where the lead angle is 0 (zero) (hereinafter, the flat portion 22 a) and a section where the lead angle is steep (the inclined portion 22 b) are alternately continued. It is formed to do.

  Further, as shown in FIG. 1B, each thread portion 21c, which is a portion of the pressure side flank 21 that switches from the flat portion 21a to the inclined portion 21b in a mountain shape, has a flat portion 21a of the pressure side flank 21. When slidably contacting the mating member, it plays a role of exerting a screw locking function by biting into the mating member.

  The thread 20 of the step lock bolt 10 configured as described above is rolled by a known rolling machine having a fixed flat die 30 and a moving flat die 40 which are a pair of flat dies. It is formed. Here, the fixed side flat die 30 and the moving side flat die 40 will be described with reference to FIGS. FIG. 2 is an explanatory diagram of the principle of manufacturing the thread 20 of the step lock bolt 10 by rolling using the fixed flat die 30 and the moving flat die 40. FIG. 3A is a partial sectional view of the rolling processed surface 31 of the fixed flat die 30 as seen from the side, and FIG. 3B shows the rolling processed surface 31 of the fixed flat die 30 as viewed from the front. It is a partial front view. FIG. 4 is a cross-sectional view taken along line 4-4 shown in FIG.

  Both flat dies 30 and 40 are formed in a substantially rectangular thick plate shape from a metal material such as die steel suitable for rolling, and the opposing rolling processed surfaces 31 and 41 are provided with step lock bolts 10. A plurality of protrusions 32 and 42 having a shape almost opposite to the shape when the screw thread 20 is developed on a plane are provided in a substantially straight line having a certain inclination with respect to the side of the rectangle (FIG. 2). FIG. 3 and FIG. Since the rolling processed surface 31 of the fixed side flat die 30 and the rolling processed surface 41 of the moving side flat die 40 are symmetrical with each other, the rolling processed surface 31 of the fixed side flat die 30 will be represented below. To explain.

  As shown in FIGS. 3 and 4, each protrusion 32 on the rolling surface 31 has a flank 33 having a shape almost opposite to the pressure side flank 21 for rolling the pressure side flank 21 of the thread 20. Are provided, and a flank 34 having a shape substantially opposite to that of the play side flank 22 is provided for rolling the play side flank 22 of the screw thread 20.

  The flank 33 is provided with flat protrusions 33a and inclined protrusions 33b that are substantially opposite to the flat part 21a and the inclined part 21b of the pressure side flank 21 so as to alternately continue. Further, the flank 34 is provided with flat protrusions 34a and inclined protrusions 34b that are substantially opposite to the flat part 22a and the inclined part 22b of the play side flank 22 so as to be alternately continued. Yes.

  And in each site | part which switches from the flat protrusion 33a of the flank 33 to the inclined protrusion 33b in a trough shape, the trough protrusion of the shape substantially opposite to the thread part 21c of the pressure side flank 21 is provided. 33c is formed.

FIG. 5 is a conceptual diagram for explaining electric discharge machining of the rolling processed surface 31 of the fixed flat die 30 by the electric discharge machining electrode 50. FIG. 6 is an explanatory diagram for explaining the shape of the plurality of discharge machining protrusions 51 in the electric discharge machining electrode 50.
Each protrusion 32 on the rolling process surface 31 of the fixed flat die 30 configured as described above is obtained by subjecting the rolling process surface 31 to electric discharge machining with a known electric discharge machining apparatus having the electric discharge machining electrode 50. (See FIG. 5). The electric discharge machining electrode 50 is made of a metal material (electrode material) such as a copper alloy that is weaker than die steel and suitable for electric discharge machining, and the electric discharge machining electrode 50 includes a fixed-side flat die. A plurality of EDM protrusions 51 having a shape substantially opposite to each of the 30 protrusions 32 are provided in a substantially straight line having a certain inclination with respect to the rectangular side (see the hatched portion in FIG. 6). .

  As shown in FIG. 6, each electric discharge machining protrusion 51 is provided with flanks 52 and 53 having shapes substantially opposite to those of the flanks 33 and 34 for electric discharge machining of the flank 33 and 34 of each protrusion 32. ing.

  The flank 52 is provided with flat discharge portions 52a and inclined discharge portions 52b having substantially opposite shapes to the flat protrusion portions 33a and inclined protrusion portions 33b of the flank 33 so as to be alternately continuous. Yes. Further, the flank 53 is provided with flat discharge portions 53a and inclined discharge portions 53b, which are substantially opposite to the flat protrusion portions 34a and inclined protrusion portions 34b of the flank 34, so as to be alternately continued. It has been.

  Then, at each portion where the flat discharge portion 52a of the flank 52 switches from the flat discharge portion 52a to the inclined discharge portion 52b, a mountain-shaped discharge portion 52c having a shape almost opposite to the valley-shaped protrusion 33c of the flank 33 is formed. Has been.

  The electric discharge machining electrode 50 configured as described above is formed by being cut by a known cutting device having the cutting blade 60.

  At this time, as can be seen from FIG. 6, when cutting the flat discharge portion 52a and the inclined discharge portion 52b with the cutting blade 60, the tip of each mountain-shaped discharge portion 52c in the flank 52 is cut. It is formed in a mountain shape so as to have a corner portion protruding outward without being formed in an R shape according to the shape of the.

  In the electric discharge machining apparatus employing the electric discharge machining electrode 50 machined in this way, the electric discharge machining electrode 50 is placed near the roll machining surface 31 of the fixed flat die 30 so that the roll machining surface 31 is formed. EDM is performed (see FIG. 5). When the flat protrusion 33a and the inclined protrusion 33b of each protrusion 32 are formed by this electric discharge machining, each trough protrusion 33c is formed into an R shape by each mountain discharge 52c. It is formed to be angular without any problems.

  Further, each protrusion 42 on the rolling processed surface 41 of the moving side die 40 is also processed by the above electric discharge machining apparatus employing the electric discharge machining electrode cut as described above. By doing so, it is similarly formed.

  After the fixed flat die 30 and the moving flat die 40 to be processed in this way are arranged so that the rolling processed surface 31 and the rolled processed surface 41 face each other at a predetermined interval, A material to be rolled for rolling the step lock bolt 10 is inserted between the rolled surface 41. Then, the thread 20 of the step lock bolt 10 is rolled (see FIG. 2) by moving the moving-side flat die 40 in the α direction with the rolling processing device.

  At this time, the tip end portion of each thread-like screw portion 21c in the pressure side flank 21 is formed so as to have a corner portion protruding outward without being formed into an R shape by each valley-like protrusion strip portion 33c. When the flat portion 21a is in sliding contact with the mating member, each thread portion 21c is likely to bite into the mating member.

  As described above, the pair of flat dies 30 and 40 according to the present embodiment includes the both flank 21 and 22 formed so that the flat portions 21a and 22a and the inclined portions 21b and 22b are alternately continued. A die for rolling the thread 20 of the lock bolt 10. In the fixed flat die 30, the flat protrusions 33 a and the inclined protrusions 33 b on the rolling processed surface 31 are flat for each electric discharge machining protrusion 51 provided on the electric discharge machining electrode 50. It is formed by electric discharge machining by the discharge part 52a and the inclined discharge part 52b, respectively.

  At this time, each valley-shaped protrusion 33c that switches from the flat protrusion 33a to the inclined protrusion 33b on the rolling processed surface 31 is inclined from the flat discharge part 52a of the electrode 50 for electric discharge machining. It is formed by electric discharge machining with each mountain-shaped discharge part 52c switching to a mountain-shaped discharge part 52b.

  Since each said mountain-shaped discharge part 52c is formed in a mountain shape, when processing each flat discharge part 52a and each inclined discharge part 52b in the electrode 50 for electric discharge machining by cutting using the cutting blade 60, the above-mentioned The tip of each mountain-shaped discharge part 52c is formed so as to have a corner that protrudes outward without being formed into an R shape.

  In order to form the flat protrusions 33a and 34a and the inclined protrusions 33b and 34b on the rolling processed surface 31 of the fixed flat die 30 with the electrode 50 for electric discharge machining processed in this way. When the rolling processed surface 31 is subjected to electric discharge machining, as described above, the tip of each mountain-shaped discharge portion 52c is formed to have a corner that protrudes outward. The protruding protrusion 33c is formed to be angular without being formed into an R shape. Further, the rolling processed surface 41 of the moving side flat die 40 is formed in the same manner.

A screw having pressure side flank 21 formed so that flat portions 21a and inclined portions 21b are alternately continued to step lock bolt 10 with fixed side flat die 30 and moving side flat die 40 processed in this way. When the crest 20 is rolled, the tip of each crest-shaped thread portion 21c of the pressure side flank 21 is formed to have a corner that protrudes outward without being formed into an R shape. The mountain-shaped screw portion 21c is easy to bite into the counterpart member.
Therefore, it is possible to manufacture the thread 20 having an improved locking effect.

  Moreover, the electrode 50 for electric discharge machining used when electric discharge machining the fixed side flat die 30 and the moving side flat die 40 according to the present embodiment is made of an electrode material having a lower strength than the die steel, for example, a copper alloy material. It consists of electrodes. For this reason, the electrode 50 for electric discharge machining can be easily processed by using the electrode raw material whose strength is lower than that of the die steel as the electrode 50 for electric discharge machining.

  Thereby, although processes such as cutting of the electrode 50 for electric discharge machining and electric discharge machining of the rolling processed surfaces 31 and 41 of the both flat dies 30 and 40 are added, the operations of the both flat dies 30 and 40 that are difficult to work are performed. Since steps such as cutting of the rolling processed surfaces 31 and 41 are abolished, the work itself of processing the rolling processed surfaces 31 and 41 of both flat dies 30 and 40 becomes easy and workability is improved.

Further, in the machining of the electrode 50 for electric discharge machining, since the wear of the cutting blade 60 is suppressed because an electrode material having a low strength is cut, variation in the shape of the electrode 50 for electric discharge machining due to wear of the cutting blade 60 occurs. It is suppressed. For this reason, the processing accuracy of the protrusions 32 and 42 on the rolling processed surfaces 31 and 41 of the both flat dies 30 and 40 formed by the electric discharge machining using the electric discharge machining electrode 50 is improved, and the both flat dies 30 are improved. , 40 also improves the machining accuracy of the thread 20 that has been rolled.
Therefore, it is possible to manufacture the screw thread 20 with improved locking accuracy and improved machining accuracy.

In addition, this invention is not limited to the said embodiment, You may actualize as follows, and even in that case, an effect | action and effect equivalent to the said embodiment are acquired.
(1) The lead angle of the flat portion 21a of the pressure side flank 21 in the step lock bolt 10 is zero due to the flat protrusions 33a on the rolling processed surfaces 31 and 41 of the fixed flat die 30 and the moving flat die 40 ( The lead angle of the flat portion 21a has a lead angle sufficiently smaller than the lead angle of the inclined portion 21b due to the flat protrusion 33a (step protrusion). The flat protrusion 33a may be formed by electric discharge machining using a flat discharge portion 52a (step discharge portion) so as to be rolled.

(2) The plurality of electric discharge machining protrusions 51 of the electric discharge machining electrode 50 are not limited to being formed by cutting with the cutting device having the cutting blade 60, but may be, for example, machining such as grinding. You may make it process using.

FIG. 1 (A) is a perspective view showing a step lock bolt according to the present embodiment, and FIG. 1 (B) is an enlarged perspective view of the thread of FIG. 1 (A). It is principle explanatory drawing which manufactures the thread of a step lock bolt by rolling using a fixed side flat die and a movement side flat die. Fig. 3 (A) is a partial cross-sectional view of the fixed-side flat die as viewed from the side, and Fig. 3 (B) is a partial front view of the fixed-side flat die as viewed from the front. is there. FIG. 4 is a cross-sectional view taken along line 4-4 shown in FIG. It is a conceptual diagram for demonstrating the electrical discharge machining of the rolling process surface of the fixed side flat die by the electrical discharge machining electrode. It is explanatory drawing explaining the shape of the some protrusion for electrical discharge machining in the electrode for electrical discharge machining. It is explanatory drawing explaining the shape of the rolling process surface in a pair of conventional flat die for rolling a step lock bolt.

Explanation of symbols

10 ... Step lock bolt 20 ... Thread 21 ... Pressure side flank 21a ... Flat part (section with loose lead angle)
21b: Inclined part (a section with a steep lead angle)
21c ... Mounted screw portion 30 ... Fixed-side flat dies 31, 41 ... Rolling surfaces 32, 42 ... Projections 33, 34 ... Flanks 33a, 34a ... Flat projections (step projections)
33b, 34b ... inclined projection 33c ... valley projection 40 ... moving side flat die 50 ... discharge machining electrode 51 ... discharge machining projection 52, 53 ... flank 52a, 53a ... flat discharge (step Discharge section)
52b, 53b ... inclined discharge part 52c ... mountain-like discharge part 60, 130 ... cutting blade

Claims (4)

A pair of dies having a plurality of protrusions for rolling a thread portion having a flank formed such that a section having a loose lead angle and a steep section are alternately continued,
In the plurality of protrusions, step-like protrusions for rolling a section with a loose lead angle and inclined protrusions for rolling a section with a steep lead angle are alternately continuous. Formed to
The dice characterized in that the step-like protrusions and the inclined protrusions are formed by electric discharge machining using step-like discharge parts and inclined electric discharge parts provided on an electric discharge machining electrode.   The die according to claim 1, wherein the electric discharge machining electrode is made of an electrode material having a strength lower than that of the die steel.   The stepped protrusions are formed by electric discharge machining by the stepped discharge part so that the lead angle of the section having a loose lead angle is rolled to zero (flat) by the stepped protrusions. The die according to claim 1 or 2, wherein A method of manufacturing a pair of dies having a plurality of protrusions for rolling a thread portion having a flank formed such that a section having a loose lead angle and a steep section are alternately continued,
Step-like protrusions for rolling the section having a loose lead angle by means of electric discharge machining with the step-like discharge part and the inclined discharge part provided on the electrode for electric discharge machining, the plurality of protrusions of both dies. And a method of manufacturing a die, comprising: an electric discharge machining step in which inclined protrusions are alternately formed in order to perform rolling processing on a section having a steep lead angle.

Images